20215436761 has 9 divisors (see below), whose sum is σ = 21892089981. Its totient is φ = 18658696992.

The previous prime is 20215436699. The next prime is 20215436767. The reversal of 20215436761 is 16763451202.

The square root of 20215436761 is 142181.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 676988361 + 19538448400 = 26019^2 + 139780^2 .

It is not a de Polignac number, because 20215436761 - 2²⁷ = 20081219033 is a prime.

It is a super-2 number, since 2×20215436761² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20215436761.

It is not an unprimeable number, because it can be changed into a prime (20215436767) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1842885 + ... + 1853821.

Almost surely, 2^20215436761 is an apocalyptic number.

20215436761 is the 142181-st square number.

20215436761 is the 71091-st centered octagonal number.

It is an amenable number.

20215436761 is a deficient number, since it is larger than the sum of its proper divisors (1676653220).

20215436761 is an frugal number, since it uses more digits than its factorization.

20215436761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21900 (or 10950 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 37.

Adding to 20215436761 its reverse (16763451202), we get a palindrome (36978887963).

It can be divided in two parts, 20215 and 436761, that added together give a 4-th power (456976 = 26⁴).

The spelling of 20215436761 in words is "twenty billion, two hundred fifteen million, four hundred thirty-six thousand, seven hundred sixty-one".