21025401515 has 16 divisors (see below), whose sum is σ = 26004014688. Its totient is φ = 16307847936.

The previous prime is 21025401487. The next prime is 21025401541. The reversal of 21025401515 is 51510452012.

It is a cyclic number.

It is not a de Polignac number, because 21025401515 - 2⁸ = 21025401259 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 148442 + ... + 253151.

It is an arithmetic number, because the mean of its divisors is an integer number (1625250918).

Almost surely, 2^21025401515 is an apocalyptic number.

21025401515 is a deficient number, since it is larger than the sum of its proper divisors (4978613173).

21025401515 is a wasteful number, since it uses less digits than its factorization.

21025401515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401918.

The product of its (nonzero) digits is 2000, while the sum is 26.

Adding to 21025401515 its reverse (51510452012), we get a palindrome (72535853527).

The spelling of 21025401515 in words is "twenty-one billion, twenty-five million, four hundred one thousand, five hundred fifteen".