21477450156661 has 4 divisors (see below), whose sum is σ = 21477493144800. Its totient is φ = 21477407168524.

The previous prime is 21477450156649. The next prime is 21477450156683. The reversal of 21477450156661 is 16665105477412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21477450156661 - 2³⁵ = 21443090418293 is a prime.

It is a super-2 number, since 2×21477450156661² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21477450156061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20735731 + ... + 21746848.

It is an arithmetic number, because the mean of its divisors is an integer number (5369373286200).

Almost surely, 2^{21477450156661} is an apocalyptic number.

It is an amenable number.

21477450156661 is a deficient number, since it is larger than the sum of its proper divisors (42988139).

21477450156661 is an equidigital number, since it uses as much as digits as its factorization.

21477450156661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42988138.

The product of its (nonzero) digits is 8467200, while the sum is 55.

The spelling of 21477450156661 in words is "twenty-one trillion, four hundred seventy-seven billion, four hundred fifty million, one hundred fifty-six thousand, six hundred sixty-one".