21402889531 has 4 divisors (see below), whose sum is σ = 21900631192. Its totient is φ = 20905147872.

The previous prime is 21402889489. The next prime is 21402889567. The reversal of 21402889531 is 13598820412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21402889531 - 2⁹ = 21402889019 is a prime.

It is a super-2 number, since 2×21402889531² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (43), and also a Moran number because the ratio is a prime number: 497741617 = 21402889531 / (2 + 1 + 4 + 0 + 2 + 8 + 8 + 9 + 5 + 3 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21402889231) 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, 248870766 + ... + 248870851.

It is an arithmetic number, because the mean of its divisors is an integer number (5475157798).

Almost surely, 2^21402889531 is an apocalyptic number.

21402889531 is a deficient number, since it is larger than the sum of its proper divisors (497741661).

21402889531 is an equidigital number, since it uses as much as digits as its factorization.

21402889531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497741660.

The product of its (nonzero) digits is 138240, while the sum is 43.

The spelling of 21402889531 in words is "twenty-one billion, four hundred two million, eight hundred eighty-nine thousand, five hundred thirty-one".