21951070928809 has 27 divisors (see below), whose sum is σ = 24384897024663. Its totient is φ = 19745294236800.

The previous prime is 21951070928719. The next prime is 21951070928863. The reversal of 21951070928809 is 90882907015912.

The square root of 21951070928809 is 4685197.

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

It can be written as a sum of positive squares in only one way, i.e., 9856868389225 + 12094202539584 = 3139565^2 + 3477672^2 .

It is not a de Polignac number, because 21951070928809 - 2¹¹ = 21951070926761 is a prime.

It is a super-2 number, since 2×21951070928809² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21951070928869) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 4999103004 + ... + 4999107394.

Almost surely, 2^{21951070928809} is an apocalyptic number.

21951070928809 is the 4685197-th square number.

21951070928809 is the 2342599-th centered octagonal number.

It is an amenable number.

21951070928809 is a deficient number, since it is larger than the sum of its proper divisors (2433826095854).

21951070928809 is an frugal number, since it uses more digits than its factorization.

21951070928809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8998 (or 4499 counting only the distinct ones).

The product of its (nonzero) digits is 6531840, while the sum is 61.

The spelling of 21951070928809 in words is "twenty-one trillion, nine hundred fifty-one billion, seventy million, nine hundred twenty-eight thousand, eight hundred nine".