21051534 has 32 divisors (see below), whose sum is σ = 48842496. Its totient is φ = 5924160.

The previous prime is 21051529. The next prime is 21051599. The reversal of 21051534 is 43515012.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 21051534.

It is a congruent 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, 927 + ... + 6554.

It is an arithmetic number, because the mean of its divisors is an integer number (1526328).

Almost surely, 2^21051534 is an apocalyptic number.

21051534 is an abundant number, since it is smaller than the sum of its proper divisors (27790962).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21051534 is a wasteful number, since it uses less digits than its factorization.

21051534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7560.

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 21051534 is about 4588.1950699594. The cubic root of 21051534 is about 276.1179132808.

Adding to 21051534 its reverse (43515012), we get a palindrome (64566546).

The spelling of 21051534 in words is "twenty-one million, fifty-one thousand, five hundred thirty-four".