21428290957 has 4 divisors (see below), whose sum is σ = 21428590716. Its totient is φ = 21427991200.

The previous prime is 21428290937. The next prime is 21428290979. The reversal of 21428290957 is 75909282412.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 12647476521 + 8780814436 = 112461^2 + 93706^2 .

It is a cyclic number.

It is not a de Polignac number, because 21428290957 - 2¹¹ = 21428288909 is a prime.

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 21428290957.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21428290937) 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, 26673 + ... + 208729.

It is an arithmetic number, because the mean of its divisors is an integer number (5357147679).

Almost surely, 2^21428290957 is an apocalyptic number.

It is an amenable number.

21428290957 is a deficient number, since it is larger than the sum of its proper divisors (299759).

21428290957 is a wasteful number, since it uses less digits than its factorization.

21428290957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 299758.

The product of its (nonzero) digits is 725760, while the sum is 49.

The spelling of 21428290957 in words is "twenty-one billion, four hundred twenty-eight million, two hundred ninety thousand, nine hundred fifty-seven".