20521764 has 18 divisors (see below), whose sum is σ = 51874550. Its totient is φ = 6840576.

The previous prime is 20521747. The next prime is 20521777. The reversal of 20521764 is 46712502.

It can be written as a sum of positive squares in only one way, i.e., 19289664 + 1232100 = 4392^2 + 1110^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×20521764² = 842285595343392, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 284989 + ... + 285060.

Almost surely, 2^20521764 is an apocalyptic number.

It is an amenable number.

20521764 is an abundant number, since it is smaller than the sum of its proper divisors (31352786).

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

20521764 is a wasteful number, since it uses less digits than its factorization.

20521764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 570059 (or 570054 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The square root of 20521764 is about 4530.0953632346. The cubic root of 20521764 is about 273.7820028889.

The spelling of 20521764 in words is "twenty million, five hundred twenty-one thousand, seven hundred sixty-four".